Linux as a PACS Server for Nuclear Medicine

Linux is being used in a Taiwan hospital as a server for medical images and as a firewall.

Many Linux users are not likely to be
familiar with nuclear medicine, but it plays a major part in the
medical field today. I am a physician and will describe my
experience with Linux in the Nuclear Medicine Department of Chang
Gung Memorial Hospital, Kaohsiung, Taiwan. I hope the information
will be useful for novice Linux users (I was a novice two and a
half years ago).

Before describing my Linux experience in nuclear medicine, I
have to mention the background of medical-image standards including
PACS, Interfile and DICOM. No standard existed among the image
formats of different CT (computerized tomography), MR (magnetic
resonance) and gamma camera vendors before 1985. After recognizing
the need for standards to facilitate multi-vendor connectivity and
PACS (Picture Archiving and Communication System), the American
College of Radiologists (ACR) and the National Electrical
Manufacturers Association (NEMA) proposed the first standard
ACR/NEMA 1.0 in 1985, ACR/NEMA 2.0 in 1988 and then ACR/NEMA 3.0
(well-known as DICOM 3.0).

DICOM 3.0 is the current standard, and almost all vendors
implement DICOM 3.0 in their new product lines, although many other
old image instruments are still not DICOM 3.0 compatible. Another
standard format in the nuclear medicine field is Interfile. Like
DICOM 3.0, Interfile is a specified file format, but, unlike DICOM
3.0, Interfile is not a communication protocol. The network
protocol of DICOM 3.0 is built on top of TCP/IP, so DICOM clients
can query/retrieve image data from a DICOM server and can also
store image data on the server through the Internet if properly
connected. Interfile is simply an interim file format of nuclear
medicine. If nothing else, it proposed a standard for gamma camera
vendors to follow, but what about the future? DICOM is the best way
to go. If you have an interest in medical image formats, please
refer to the Medical Image Format FAQ
(http://idt.net/~dclunie/medical-image-faq/html/index.html),
maintained by David Clunie, M.D., for further information.

In the Diagnostic Nuclear Medicine department, after
intravenous injection or oral ingestion of radionuclides, patients
are put under a gamma camera to have pictures taken. A gamma camera
picks up gamma-rays emitted from the radionuclides to make up the
images. There are many gamma camera vendors in the market. The
following is a list of them and the operating systems they
use:

The network protocol for Macintosh is AppleTalk, for OS/2 it
is NetBIOS and for UNIX it is TCP/IP. Due to the prevalence of the
Internet, all operating systems used today also support TCP/IP.
Network protocols for computers are used for communication in the
same way language is used by people. Under the same network
protocol, different computers can exchange data with one another.

Chung Gung Memorial Hospital, Kaohsiung, Taiwan, is a medical
center with more than 1,000 beds. One IP address is assigned to the
Nuclear Medicine Department. We have three gamma cameras. The
oldest one is the GE STARCAM which uses a proprietary OS, one
Siemens ICON triple-head gamma camera and one Elscint Varicam
dual-head gamma camera. The Elscint Varicam is a brand new gamma
camera, installed before I left the hospital.

After learning about Linux two and a half years ago, I
realized it would be the perfect server for gamma cameras. Since
Linux is a UNIX clone, it offers TCP/IP networking. In addition,
Netatalk (AppleTalk protocol for UNIX) allows Linux directories to
be mounted by Macintosh, and SAMBA (SMB is NetBIOS over TCP/IP)
allows OS/2, Windows 95 and Windows NT to use the services at Linux
and vice versa. TCP/IP, AppleTalk and SMB (server message block)
are all available in Linux; thus, Linux can communicate with all
gamma camera computers except some old and proprietary ones. I will
describe later how to solve the problem of retrieving the image
data from proprietary computer operating systems.

At the time I set up Linux as a PACS server for our Nuclear
Medicine department, our Siemens ICON could export Interfile image
files but didn't offer the DICOM function. The Elscint Varicam
offered DICOM functions and the GE Starcam offered neither
Interfile nor DICOM. Using the image translation software GAMMACON
from MITA, the problems of the proprietary image file data were
solved.

GAMMACON is a program that runs under the MS-DOS environment.
It reads and writes different proprietary, Interfile and DICOM
image files to and from 8-inch, 5.25-inch or 3.5-inch diskettes and
the network or hard disk. GAMMACON uses a security hardware key
attached to the PC printer port to prevent software piracy. After
modifying the configuration file of the Linux DOS Emulator,
GAMMACON runs smoothly under Linux. Combined with the network
capacities of Linux, we could translate the GE Starcam image files
archived on 3.5-inch floppy disks into Interfile, and then process
them on the Siemens ICON or the Elscint Varicam. Due to the
limitations of GAMMACON, only one program could be run at a time.
The security hardware key is locked by GAMMACON. After the needed
programs are installed, Siemens ICON could easily mount the Linux
shared directories from the CHOOSER via Netatalk. Elscint Varicam
OS/2 could also mount the Linux shared directories as a network
disk (via SAMBA). For other gamma cameras that use UNIX, such as
Picker or ADAC, mounting the directories via NFS is routine
work.

To read the GE Starcam files off-line, I could bring the
floppy disks from the GE Starcam to Linux, then use GAMMACON to
translate the GE Starcam files into Interfile, DICOM or GIF format.
It sounds perfect. Even for gamma cameras that are not DICOM
compatible, we still offer a convenient way to solve the image file
exchanges in nuclear medicine by using the specific functions of
the software from different vendors to process the images. Before I
left Chung Gung Memorial Hospital last year, I worked on the DICOM
Query/Retrieve (DICOM client) function on Linux—a hard job for me,
since I have no programming background. The Swansea University in
Wales offers the DICOM server service on Linux; perhaps others do
too.

Finished? No, I mentioned earlier that one IP address is
assigned to our Nuclear Medicine department. I installed two NE2000
compatible cards in this Linux PC PACS server and recompiled the
Linux kernel to enable the IP masquerade function. One network card
is used with the IP address we were assigned and the other network
card is assigned to an internal network address. All the gamma
camera computers, the Macintoshes and the Windows 95 PCs in our
office belong to the internal network and can access the Internet
seamlessly through the Linux IP masquerade. The Linux IP masquerade
forms a firewall to prevent invasion from the Internet. The
limitation of one IP address is no longer present.

Combined with the Apache WWW server and mSQL, we use the
GIF-format nuclear medicine images converted from GAMMACON to make
all the diagnostic reports available as HTML documents available to
the registered medical doctors.

Hylafax is a free fax server for Linux, and it also supports
many other operating systems such as Macintosh and MS Windows.
Several colleagues of mine are quite happy with Hylafax, since they
can easily send a fax from their PCs. You may wonder why I didn't
mention DNS or a mail server. Our hospital set a proxy server to
allow only the WWW browser to access the external world and prevent
hacker destruction, so we must exclusively use the mail server
offered by our hospital. They set the proxy and mail server to the
same SUN Ultra SPARC.

Is Linux difficult? No. Take me as an example. I was a total
computer newbie two and a half years ago, and yet I used Linux in
my daily work. I am sure others could do the same. I would like to
thank all of the people who devote their efforts to Linux and free
software.

The author,
Cheng-Ta Wu
was a nuclear physician
and is now in general practice at Feng Shan, Kaohsiung County,
Taiwan. He lives with his parents, two brothers and a dog. He is
interested in traveling, music and swimming. If you come across him
while he is traveling, please mention you are a Linux user. He can
be reached via e-mail at chengtaw@mail.euphoria.com.tw.

Thanks for this great article. Cheng-Ta, before to leave you worked on the Dicom services on Linux, could you indicate, if you was successfull ? or did you use the DICOM solution provide by the Swansea University ?